The objective of this project is to develop a genetic profile and a genetic linkage map for the 26 inbred rat strains maintained by VRB. The genetic profile will include determination of genetic differences and similarities among the strains for various parameters, including morphology, proteins, enzymes, and immunological responses. A genetic map that defines the linkage relationships among the various loci will be developed. The principle method employed is starch-gel electrophoresis for separation of proteins and enzymes. Special mating systems including production of F1 hybrids and backcrosses will be necessary for genetic analysis of the linkage data.